1. Field of the Invention
The present invention relates generally to semiconductor devices, and more particularly to packaging semiconductor devices.
2. Description of Related Art
Integrated circuits, for example memory, are used in a wide variety of applications. Typically, memory conforms to accepted standards. For example, many memory standards are defined by the Joint Electron Device Engineering Council, also known as the JEDEC Solid State Technology Association (JEDEC). Designs for memory that conform to standards such as JEDEC standards are well known. Moreover, memory layouts and lithographic masks for standard memories are readily available. It is desirable to use such standard memory designs in an application rather than redesigning the memory specifically for a different application. However, the number of external contacts used for standard memory is determined by the standard for the memory design. The minimal size of the package sometimes is limited by the number and pitch of the contacts. This is a disadvantage of the prior art.
FIG. 1 illustrates a prior art standard (JESD79C) timing diagram for a memory bank write operation. In this standard, a first set of inputs A0-An, A10, BA0 and BA1 are used to input an address and a second set of inputs DQ and DM are used to write data values starting at the address. The data values are written several clock cycles after the address as input.
FIG. 2 illustrates a timing diagram for a memory bank read operation according to the prior art standard of FIG. 1. In this operation, inputs A0-An, A10, BA0 and BA1 are used to input an address and DQ and DQS are used to output data stored starting at that address. The data values are read several clock cycles after the address as output.
FIG. 3 illustrates a prior art bond pad layout for a memory device proposed by JEDEC. The illustration includes 79 bottom pads and 44 top pads. A variety of data (DQ, DQS and DM), address (A, BA) pads are illustrated. This particular configuration includes 32 DQ pads and, thus, can handle 32-bit data.